The genus Kopsia (Apocynaceae) comprises some 23 species
of shrubs and trees distributed mainly over Southeast Asia, India,
and China, of which about 16 species occur in Malaysia.1 Plants
belonging to this genus are prolific producers of a wide variety of
indole alkaloids, including many with intriguing carbon skeletons
as well as interesting biological activities.2-16 In continuation of
our ongoing studies of these plants, we wish to report the full
alkaloidal composition of the stem-bark extract of Kopsia arborea
Blume (an ornamental Kopsia, widely cultivated in gardens in
Malaysia), including the isolation, structure determination, and
biological activity of several new alkaloids.